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Nitrogen Acquisition from Atmospheric NH 3 by Lolium perenne
Author(s) -
Wollenweber B.,
Raven J. A.
Publication year - 1993
Publication title -
botanica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 0932-8629
DOI - 10.1111/j.1438-8677.1993.tb00336.x
Subject(s) - lolium perenne , shoot , ammonia , nitrogen , chemistry , dissolution , environmental chemistry , botany , poaceae , biochemistry , biology , organic chemistry
Ammonia (NH 3 ) is the third most abundant N species in the atmosphere and, due to various natural and anthropogenic sources, can reach high concentrations in some areas. While some plants show effects of toxicity, others are capable of using this N‐form and grow well without any utilization of soil‐N. Acquisition of atmospheric NH 3 will affect the acid‐base balance of the plants as absorption and dissolution causes an alkalinisation (production of OH − ) and assimilation of NH 3 results in an acidification (generation of H + ). As there is only a limited capacity for biochemical disposal of excess H + in shoots, pH regulation may involve H + /OH − extrusion into the media via roots and transport of (in)organic ions between roots and above‐ground parts of the plant. Our aim therefore was to assess NH 3 acquisition by Lolium perenne and to study the effects of gas phase NH 3 on growth, acid‐base balance and mineral composition of the plants. The experiments therefore included application of a range of 14 NH 3 to the shoots and of 15 N as NO 3 − , NH 4 + or NH 4 NO 3 to the roots, from which the amount of gas phase NH 3 acquisition could be quantified. Analysis of the mineral composition provided data for calculation of acid‐base balance as well as for water use efficiencies of the plants. The results indicate that over the range of NH 3 supplied, plants from all treatments could utilize gas‐phase NH 3 as demonstrated by increases in growth and in N and C use efficiencies. Plants receiving NO 3 − via their roots had a higher capacity to use gaseous NH 3 than those growing with NH 4 + . NH 3 assimilation in shoots reduced both the acid load with NH 4 + nutrition and the alkaline load with NO 3 − supply to the roots. The results of the experiments are discussed in relation to possible acid‐base regulation mechanisms of the whole plant.